16002-25-8Relevant articles and documents
Stress relaxation via addition-fragmentation chain transfer in high T g, high conversion methacrylate-based systems
Park, Hee Young,Kloxin, Christopher J.,Abuelyaman, Ahmed S.,Oxman, Joe D.,Bowman, Christopher N.
, p. 5640 - 5646 (2012)
To reduce shrinkage stress which arises during the polymerization of cross-linked polymers, allyl sulfide functional groups were incorporated into methacrylate polymerizations to determine their effect on stress relaxation via addition-fragmentation chain transfer (AFCT). Additionally, stoichiometrically balanced thiol and allyl sulfide-containing norbornene monomers were incorporated into the methacrylate resin to maximize the overall functional group conversion and promote AFCT while also enhancing the polymer's mechanical properties. Shrinkage stress and reaction kinetics for each of the various functional groups were measured by tensometry and Fourier-transform infrared (FTIR) spectroscopy, respectively. The glass transition temperature (T g) and elastic moduli (E′) were measured using dynamic mechanical analysis. When the allyl sulfide functional group was incorporated into dimethacrylates, the polymerization-induced shrinkage stress was not relieved as compared with analogous propyl sulfide-containing resins. These analogous propyl sulfide-containing monomers are incapable of undergoing AFCT while having similar chemical structure and cross-link density to the allyl sulfide-containing methacrylates. Here, a monomethacrylate monomer that also contains a cyclic allyl sulfide (PAS) was found to increase the cross-linking density nearly 20 times as compared to an analogous monomethacrylate in which the allyl sulfide was replaced with an ethyl sulfide. Despite the much higher cross-link density, the PAS formulation exhibited no concomitant increase in stress. Thiol-norbornene resins were copolymerized in PAS to promote AFCT as well as to synergistically combine the ring-opening benefits associated with the thiol-ene reaction. AFCT resulted in a 63% reduction of polymerization stress and a 45 °C enhancement of the glass transition temperature in the allyl sulfide-containing thiol-norbornene-methacrylate system compared with rubbery dimethacrylates. When compared with conventional glassy dimethacrylates, this combined system has less than 10% of the typical shrinkage stress level while having similarly excellent mechanical properties.
High Tg sulfonated insertion polynorbornene ionomers prepared by catalytic insertion polymerization
Pierre, Florian,Commarieu, Basile,Tavares, Ana C.,Claverie, Jerome
, p. 91 - 97 (2016/02/10)
A simple method to synthesize high Tg sulfonated ionomers based on catalytic insertion polynorbornene is reported. Copolymers of norbornene and 5-methyl alcohol norbornene (endo:exo = 82:18) or 5-methyl bromide norbornene (endo:exo = 86:14) as well as terpolymers of norbornene, 5-methyl alcohol norbornene and 5-hexyl norbornene are prepared using a cationic Pd catalyst. These copolymers are then thioacetylated. Using hydrogen peroxide as oxidant, a sulfonated polynorbornene is obtained. Ionomers containing as much as 30 mol% SO3H and with Tgs above 200 °C are obtained in a four-step procedure of overall 40-75% yield.
Versatile route to functionalized vinylic addition polynorbornenes
Martinez-Arranz, Sheila,Albeniz, Ana C.,Espinet, Pablo
experimental part, p. 7482 - 7487 (2011/11/12)
Vinylic addition polynorbornenes bearing functional groups can be obtained in a versatile way by nucleophilic substitution of a halogen in new vinylic haloalkyl polynorbornenes. The latter are obtained by vinylic homo and copolymerization of norbornene and haloalkyl norbornenes catalyzed by [Ni(C 6F5)2(SbPh3)2]. This method circumvents the problem of catalyst deactivation encountered in classical copolymerizations with polar monomers. The content of substituted monomer in the copolymers is in the range 26-59%, depending on the monomer ratio in the feed. Nucleophilic substitution reactions afford polymers with ester, cyano, phenylthio, or azido groups in the same wide range of composition. Click chemistry on the azido polynorbornenes give polynorbornenes with pendant triazole groups.
